Implantable medical devices, such as pacemakers, implantable cardioverter defibrillators (ICD), etc., are implanted in patients in order to supply electrical pulses to a patient's heart to maintain a consistent heartbeat. Some devices may additionally function as a defibrillator, detecting cardiac arrhythmia and providing an extra surge of electricity to prevent heart damage. These devices are inserted in a patient's chest and electrical leads extending from the device, are thread through a vein to the patient's heart. The device housing and the leads are hermetically sealed in order to prevent the electrical connections from shorting due to bodily fluids. The electrical leads have electrodes, defibrillator coils, and/or sensors placed at various positions on and within the heart. The electrodes and defibrillator coils provide electrical current to stimulate the heart and the sensors determine whether a pulse is needed and how much current should be applied.
The electrical leads are thread through the housing of the device to reach the circuitry held within. The leads are then secured into position within the housing by a set screw received within the housing. The set screw is sealed from bodily fluids using a septum, which is made of silicone rubber and has a resealable split. The split allows a screwdriver, wrench or other tool to extend through the septum to tighten the set screw, the septum resealing after the tool is withdrawn from the case. Because the septum is made of silicone, the tool is able to push the silicone rubber aside to reach and tighten the set screw. However, the soft silicone rubber may prevent the tool from making full contact with the screw, as the soft material may be pulled downwards with the tool, covering the contact between the tool and the set screw. Additionally, as the tool enters the septum, small pieces of the silicone rubber are pulled off as the tool is pushed down. This tearing results in pieces of silicone rubber pushed into the socket of the set screw, which may cause the set screw to be stripped. Additionally, the cored silicone rubber causes the septum to contain holes and no longer be completely sealed, allowing bodily fluids to enter the septum. This leakage can potentially cause the electrical connections to short and cause the device to malfunction. Therefore, there is a need in the art for a septum that seals the electrical connections and allows a tool to enter in order to tighten a set screw without damaging the septum.